Stabilization of petroleum distillate fuels by oxidative treatment



United States Patent 3,479,163 STABILIZATION 0F PETROLEUM DISTILLATEFUELS BY OXIDATIVE TREATMENT Elliot A. Vogelfanger, Edison, and ThomasJ. Wallace,

Elizabeth, N.J., assignors to Esso Research and Engineering Company, acorporation of Delaware No Drawing. Filed Jan. 3, 1966, Ser. No. 518,033

Int. Cl. C1011/;B01j1/16 U.S. C]. 44-64 12 Claims ABSTRACT OF THEDISCLOSURE The present invention relates to the stabilization ofpetroleum distillate fuels containing olefinic unsaturated componentsthrough an oxidative treatment. In particular, it relates to thestabilization of fuels having boiling ranges within the boiling range ofbetween about 75 F. and about 750 F. whereby it is possible to improvethe stability of such fuels by oxidative degradation and to thus greatlyalleviate the gum-forming tendencies of such fuels when stored orstanding under atmospheric conditions and in contact with theatmosphere, which atmosphere contains molecular oxygen.

The petroleum industry has long recognized the instability of distillatepetroleum fuels, boiling between about 75 F. and about 750 F. or havingboiling ranges within this range, largely due to the presence ofolefinic unsaturated components in such fuels. This constitutes aserious problem in connection with the use, handling, and storage of thefuels because of the unstable constituents, chief among which are themono and diolefinie components, tend to gradually oxidize or otherwisereact. For example, polymerization or copolymerization occurs duringstorage to form gums, sludges, and/or sediments which either precipitateout of the fuel or which remain in solution in the fuel and are laterdeposited through vaporization or combustion of the fuels in fuel lines,carburetors, pistons, cylinder walls and other surfaces in internalcombustion engines thus causing breakdown in lubrication and a generalgumming up in internal combustion engines. Such clogging and depositionof either precipitate or dissolved gums or sludge which have formed as aresult of the co-oxidation or oxidation of the olefinic componentsnecessitates the disassembling of the engine and the cleaning of allmoving parts including carburetors fuel lines, filters and the like.This becomes an extremely expensive operation and entails time consumingeffort. In the past, this has sometimes been controlled to some extentthrough the addition of antioxidants to the petroleum distillate fuelscontaining the olefinic components.

In a copending application, Ser. No. 517,908 filed Jan. 3, 1966 byThomas 1. Wallace and Norman Friedman entitled Oxidative Treatment ofPetroleum Distillate Fuels Containing Olefinic Unsaturated Components, anew and improved method of treating such unsaturated petroleumdistillates, in order to accelerate the formation of gum and sludgethrough polymerization and/or copolymerization of the olefiniccomponents thereof, there is disclosed a use of certain arylhydrazones.It is'shown therein that once the major portion of the readily oxidiziceable and polymerizable olefinic components are removed as polymers,either soluble or insoluble in" nature, the resultant distillate fuel isstabilized against further atmospheric oxidative degradation to a largeextent. In that application it is directed to add between about 0.1 andabout 1% by weight, preferably between about 0.3 wt. percent and about0.6 wt. percent of one or more specific arylhydrazones in the presenceof molecular oxygen, i.e., air, which may either be dissolved in thefuels or in contact with the fuels during such treatment. Neither thetime of contact nor the temperature is important in such treatment butit is preferred to use a temperature of from atmospheric up to about F.for a sufiicient time of contact of the arylhydrazones with the olefinicfeedstocks to allow for substantial oxidative polymerization orcopolymerization of the olefinic constituents thereof. The time ofcontact may range anywhere from between about 30 minutes up to severalhours, for example, up to 8 to 50 hours or even longer. The length oftime is generally that amount of time during which substantialquantities of oxygen are consumed or taken up in the reaction. It hassubsequently been discovered that this may last up to 172 to 200 hourswhere atmosp'heric temperatures are employed.

Following the treatment the solid or existent gums are removed bysettling, decantation, centrifugation, or filtration. A subsequentatmospheric or vacuum distillation, it convenient, will result in anoverhead distillate or condensate substantially free of potential orsoluble gum, the residue containing such gum. Fuels so treated areeffectively stabilized against any substantial oxidative reactions andso they remain stable over prolonged periods of time and during actualuse. If desired, they may be stabilized against further oxidation by theuse of conventional antioxidants as additives thereto. Suchantioxidants, for example, are: 2,6-di-tertiary butyl phenol, para-aminophenol, di-phenylamine, and N,N- di-secondary butyl-paraphenylenediamine. Conventionally these are added in amounts up to about0.01 wt. percent and thus effect stabilized fuels which remain so overlong periods of time of the order of many weeks or months.

The arylhydrazones employed are those having the formula:

ary1-NH=N C RI wherein R may be a C C saturated acyclic hydrocarbonradical such as methyl, ethyl, isopropyl, propyl, butyl, isobutyl,octyl, iso-octyl, dodecyl and the like or may further be a C C saturatedcyclic aliphatic hydrocarbon radical such as cyclopentyl, cyclohexyl,cycloheptyl and the like, an aralkyl radical such as benzyl, phenethylor an aryl radical such as phenyl, naphthyl or anthryl. R may be thesame as or different from R as above defined, R and R may be jointly a CC alkylene (cycloaliphatic) radical or R may be hydrogen. It has beendiscovered, however, that R may not be an aryl radical if R is also anaryl radical. The arylhydrazine reacted with this ketonic or aldehydiccompound must be an arylhydrazine such as phenylhydrazine,naphthylhydrazine, or anthrylhydrazine. Representative hydrazonesemployed are the phenylhydrazones of cyclohexanone, cyclopentanone,benzylaldehyde, para-tolyl aldehyde, dibenzyl ketone, acetophenone,9-anthranaldehyde, l-naphthaldehyde, and Z-naphthaldehyde. Thearylhydrazones may be formed by reacting the hydrazine with a mixedketoaldehyde such as pivalyl aldehyde, a dialdehyde such asphthaldehyde, or a diketone such as cyclohexanedione orcyclopentanedione. As used in this description and accompanying claims,the definitions of R and R are intended to encompass the mixedketoaldehydes, the diketones, and the dialdehydes.

It has now been discovered that improved rates of oxidation withresultant polymerization and copolymerization can be accomplished andimproved amounts of existent and potential gums formed if there is used,in conjunction with the hydrazones mentioned above, an effective amountof one or more metallocenes. The amount of the metallocene may varyconsiderably but, in general, the distillate fuel being treated willcontain an arylhydrazone to metallocene weight ratio of between about1:1 and about :1, preferably between about 3 :l and about 6:1. Largeramounts of metallocenes may be employed with regard to the amount ofarylhydrazones used but, because of the cost of the metallocenes, therate of oxidation, and the total amount of polymerization orcopolymerization of the olefinic constituents is not sufiicientlyincreased to warrant the extra expense of using the larger amounts ofmetallocenes; the total amount of mixed treating agent used(hydrazone-i-metallocene) is preferably between about 0.1 and about 7.0wt. percent, preferably between about 0.4 and about 0.7 wt. percent. Thetwo types of additives may be premixed and added to the fuel or eitherone may be first added and the other one subsequently added.

The metallocenes are formed through the interaction of Group VIII metalinorganic salts with cyclo olefins or their simple methyl and ethylderivatives. Any metal of Group VIII of the Periodic System, accordingto Mendeleeif, may constitute the metal portion of the metallocene.Specific examples of suitable metal components of the metallocene are:iron, cobalt, nickel, ruthenium, osmium, and the like. The olefinicportion of the metallocene is preferably derived from cyclopentadienealthough other cyclo olefins such as cyclo-octadiene,cyclo-octatetraene, cyclo-butadiene and benzene, for example, are alsosuitable as reactants. Any of the conventional methods for thepreparation of the metallocenes may be employed, for example, ferrocenemay be produced by reacting ferric or ferrous chloride in ethyl etherwith a solution of cyclopentadienyl magnesium bromide or ferrouschloride may be reacted with cyclopentadiene under nitrogen at 300 F. inthe presence of alumina, molybdena, or the like in the presence ofpotassium oxide. US. Patents 2,680,756 and 2,791,597 discloserepresentative methods of preparing the metallocenes. The use ofammonium salts or of alkali metal salts of cyclopentadiene in liquidammonia followed by the addition of anhydrous metal nitrate orphthalocyanate, the metal being a Group VIII metal, results in a complexwhich loses ammonia on heating, in vacuum, to give the correspondingmetallocene. The present invention is not concerned with any particularmethod of preparing the metallocenes, any of the methods heretoforeknown being suitable for their production.

Representative metallocenes which are useful as additives, when used inconjunction with the aforementioned arylhydrazones, are the following:cyclopentadienyl iron (ferrocene), cyclopentadienyl nickel(nickelocene), cyclopentadienyl cobalt (cobaltocene), cyclopentadienylruthenium (ruthenocene), cyclopentadienyl osmium (osmocene);acylmetallocenes such as acetylforrocene, formylferrocene,benzoylferrocene, benzoylruthenocene, arylmetallocenes such asphenylferrocene, 1,3,1,3'-tetraphenylferrocene, p-ferrocenylphenol,p-ferrocenylaniline, dibenzoruthenocene; and the alkyl-substitutedcyclopentadienyl metallocenes such as methylferrocene,1,1'-diisopropylferrocene, and 1,1- trimethyleneferrocene. Themetallocenes and their method of preparation are fully disclosed inRosenblum Chemistry of the Iron Group Metallocenes, a volume in theseries The Chemistry of Organometallic Compounds, published byInterscience Publishers, a division of John Wiley & Sons (1965), whichreference work is incorporated hereinto by reference.

The oxidative treatment of the petroleum distillate fuels containingolefinic unsaturated components involving the combined use ofarylhydrazones and metallocenes, as above described and defined, appliesto a wide range of gasolines and heating oils. These may be derived fromgas oils of any desired boiling range through the conventional steamcracking, thermal cracking, or catalytic cracking of the same. Almostany cracked naphtha or heating oil contains considerable quantities ofolefinic compounds. These olefinic compounds, depending upon theparticular process by which the feed was produced, can be either cyclicor acyclic in nature. They can be mono-olefinic or di-olefinic (eitherconjugated, nonconjugated, or of the allenic type). In some casespolymeric forms of olefins are present in the cracked naphthas asproduced, generally in soluble form. Any of the cyclic or acyclicolefinic unsaturated compounds such as indene, or even styrene, will beeffectively polymerized or copolymerized through the novel arylhydrazonetreatment herein described. Typical olefins found in cracked naphthasand heating oils include the following: 2-hexene, cyclohexene, indene,1,3-hexadiene, l-pentene and 4-methyl-Z-hexene. Any number of theseolefinically unsaturated compounds other than those specificallymentioned tend to render gasoline or heating oils unstable duringstorage.

Additionally, and depending upon the source of the crude oil which hasbeen used, these distillate fuels may also contain nitrogen compoundssuch as pyrroles, indoles, aliphatic amines and pyridines; disulfides;and finally mercaptans of both aliphatic and aromatic nature. Althoughit is not intended that the instant novel process be limited by anytheory, it is believed that substantial portions of these types ofimpurities also undergo oxidative reaction involving polymerization and/or oxidative reaction involving copolymerization of those impuritieswith some of the olefinic components present and so are likewiseconverted into gums or sludges which can be removed in the same mannerand at the same time as the gums and sludges formed solely from theolefinic constituents.

The presence of other additives in the treated distillates such asantiknock agents, scavenging agents, dyes, antiicing agents, and solventoils in total additive concentration not exceeding 5% by wt. does notadversely affect the oxidative treatment with arylhydrazones andmetallocenes for the purpose of forming gums. Conversely, the treatmentwith arylhydrazones and metallocenes does not adversely affect thefunctioning of the aforementioned conventional additives for theirintended purpose, so that it is possible to successfully carry out theoxidative gum formation operation on either finished or unfinishedgasolines or heating oils, which contain the olefinic components.

Representative specific types of naphthas and heating oils to which theinvention applies are heavy catalytic naphthas, light catalyticnaphthas, No. 2 heating oil, and the like. Typical and representativechemical and physical inspections of two such naphthas are as follows:

Heavy Light;

Catalytic Catalytic N aphtha Naphtha.

Gravity, A.P.I 25 57. 9

Initial Boiling Point, F- 430 77 Final Boiling Point, 11. ResearchOctane Number Wt. percent aromatics 47. 1 11.3 Wt. percent monoolefins-diolefins (cyclic-Hwyclic) 26. 3 57. 8 Wt. percent saturates(cyclic-l-acyclic) 26.6 30. 9

Example 1 than 72 hours had been left standing for one or more days withoxygen in contact therewith so that, to some extent, they were alreadypartially oxidized and, to some extent, had partially lost theiroxidizing activity. In any case, the times of contact are those timesdeemed to have been necessary to secure substantially completeconsumption of oxygen using the particular reactants and under theparticular conditions obtaining at the time.

The data in Table I clearly point out the advantage of TABLE I.-HEAVYCATALYTIC NAPHTHA FEED (200 cc.)

Total gum (m .ll Amount cc. of feed% in grams Time of Treat.

(weight Contact Temp. Existent Potential Oxidative Reagent p C.) (Solid)(Soluble) Blank 24 25 34 844 cyclohexanone phenylhydrazone (250 cc.) 2.(1. 0) 119 605 1, 584 (Fresh) cyclohexanone phenylhydrazone... 2. 0(1.0) 72 25 977 2, 221 Plus Ferrocene 0 .1) 72 25 932 2, 321 PlusNickeloeene... 0. 2(0.1) 72 25 l, 402 2, 403 Plus Cobaltoeene 72 25 1,212 4, 794 Aeetopheuone phenylhydrazon 2. 0(1. 71 25 370 2, 820 PlusNickelocene 0. 2( 7 25 1, 378 2, 728 Plus Cobaltoceue 72 25 1, 756 3,e94 cyclopentanone phenylhydrazone 9 25 273 1, 041 (Fresh)cyclopentanone phenylhydrazone 2. 0(1. 0) 171 25 547 1, 505 Pluscobaltocene 72 25 2, 607 4, 030

with a paddle stirrer, an overhead water-cooled condenser, athermometer, and a self-sealing rubber cap. Molecular oxygen wassupplied to the vessel from a partially filled polyethylene gas balloon,through a wet-test gas meter through which oxygen was passed, connectedto a drying tower packed with a desiccating material such as Drierite(anhydrous magnesium sulfate). There was then introduced into thereaction vessel through the neck of the flask 200 to 250 cc. of naphthaand 2 to 2.5 grams of the particular phenylhydrazone and metallocene,when used. The system was then purged with oxygen, sealed with therubber cap, and the Wet-test meter adjusted to zero volume when anequilibrium pressure was established. The reaction was then started byrapid stirring and was allowed to proceed until no further oxygenconsumption could be detected on the wet-test meter. All experimentswere conducted at atmospheric pressure.

In the following tables, the column headed Existent (Solid) and thecolumn headed Potential (Soluble) added together give the total gumformed in the treating process; the existent gum being precipitated fromthe naphtha and recovered by filtration and weighed in terms ofmilligrams per 100 cubic centimeters of naphtha and the potential gumbeing soluble gum which was recovered after distilling to dryness andweighing the gum. These figures are also in terms of milligrams of gumper 100 cc. of feed.

using small amounts of metallocene in conjunction with thephenylhydrazones to increase both existent and potential gum content.For example, the existent gum of the heavy catalytic naphtha isincreased from 34 to 977 mg./ 100 cc. feed (about 30-fold) by addingabout one weight percent cyclohexanone phenylhydrazone. When a smallamount (about 0.1 wt. percent) of nickelocene is employed together withthe same phenyl hydrazone, the existent gum is increased by about45-fold to 1402 mg./ 100 cc. of feed. Similarly cobaltocene inconjunction with cyclopentanone phenylhydrazone increases the existentgum number of the heavy catalytic naphtha by about 76- fold to 2607 mg./100 cc. of feed. Significant increases in potential gum content werealso obtained by the addition of small amounts of the same metallocenesin combination with the same phenylhydrazones as seen by a comparison ofthe data in the extreme right-hand column of Table I.

Example 2 In a mannensirnilar to that described in Example 1, a lightcatalytic naphtha having the inspection above stated was treated withtwo specific cyclo olefinic phenylhydrazones with and without admixturewith various metallocenes as shown in in Table II. The time conditionsand the oxidative reagent employed, the amount of solid and soluble gumsformed and the like are shown in Table II.

TABLE II.LIGHT CATALYTIC NAPHTHA FEED (200 cc.)

Total gum (mg ./100

Amount cc. ed) in grams Time of Treat.

(weight Contact Temp Existent Potential Oxidative Reagent percent)(hours) C.) (Solid) (Soluble) Blank 24 25 6. 6 308 cyclohexanonephenylhydrazone. 2. 0(1. 0) 71 25 560 1, 361 Plus Ferrocene 0. 2 (0. 1)72 25 870 1, 256 Plus Nickelocene 0. 2 (0. 1) 72 25 624 955 Plus 0obaltocene 0. 2 (0. 1) 72 25 041 3, 552 Cyclopentonone phenylhydrazone2. 0(1. 0) 72 25 420 817 Plus Nickelocene 0. 2(0. 1) 72 25 754 l, 983Plus Cobaltocene 0. 2(0. 1) 72 25 1, 004 1, 117

In this example as well as the following examples, with respect to thetables, the designation fresh with respect to cyclohexanonephenylhydrazone or cyclopentanone phenylhydrazone is intended .todifferentiate a distinction as to time of use as between thosehydrazones and the same hydrazone used in some cases for comparativepurposes which was not fresh at the time of usage. In other words, thoseruns employing 72 hours for time of contact employed freshly preparedcycloaliphatic phenylhydrazone, whereas, those not so designated andAgain, as in Example 1, appreciable increases in existent and potentialgum content were obtained by the use of small quantities of metallocenewith phenylhydrazones in the light catalytic naphtha. For example, whilecyclohexanone phenylhydrazone alone increased the existent gum contentto 560 mg./10O cc. feed, the admixture of 0.1 wt. percent ferroceneincreased this number still further to 870 mg./100 cc. feed while, withneither additive being used, the gum content was 6.6 mg./100 cc. feed.The potential gum content of the light catalytic naphtha where the timeof contact may be either shorter or longer 75 was also increased by morethan 10-fold by the use of a catalytic quantity of cobaltocene inconjunction with cyclohexanone phenylhydrazone. Similar results werealso obtained from the cyclopentanone phenylhydrazone cobaltocenecombination.

Example 3 TABLE IIl.-REGULAR GASOLINE (200 cc.)

and R being jointly a C -C alkylene radical, the weight ratio ofarylhydrazone to metallocene being between about 1:1 and about :1, andremoving from the so treated distillate fuel at least the solid gumformed thereby.

2. A process as in claim 1 wherein the arylhydrazone used is thephenylhydrazone of cyclopentanone and the metallocene is selected fromthe group consisting of ferrocene, nickelocene and cobaltocene.

3. A process as in claim 1 wherein the arylhydrazone used is thephenylhydrazone of cyclohexanone and the metallocene is selected fromthe group consisting of ferrocene, nickelocene and cobaltocene.

4. A process as in claim 1 wherein the arylhydrazone used in thephenylhydrazone of acetophenone and the metallocene is selected from thegroup consisting of ferrocene, nickelocene, and cobaltocene.

Total gum (mg Amount cc. of feed) in grams Time of Treat. (weightContact Temp. Existent Potential Oxidative Reagent percent) (hours) C.)(Solid) (Soluble) U Blank 24 25 6. 6 3 Cyclohexanone phenylhydrazone:

500 cc. of fee 2. 5 (0. 5) 25 333 753 500 cc. of feed 0. 5 (0. 1) 51 25121 766 (Fresh) Cyclohexanone phenylhydrazone. 2.0 (1.0) 72 25 720 1,201Plus Ferrocene 0.2 (0.1) 72 25 658 1,024 Plus Nickeloceue. 0. 2 (0. 1)72 25 615 1, 048 Plus Cobaltocene. 0, 2 (0. 1) 72 25 867 l, 140Benzaldehyde phenylhydrazone 2.0 (1. 0) 72 25 549 690 Plus Ferrocene 0.2(0.1) 72 25 231 891 Plus Nickelocene. 0. 2 (0. l) 72 25 862 1, 197 PlusCobaltoceue 0.2 (0.1) 72 25 624 1,064 Acetophenone phenylhydrazone...2.0 (1.0) 72 25 329 727 Plus Niekelocene 0.2 (0.1) '72 25 908 1,422 PlusCobaltocene .1 0.2 (0. 1) 72 25 933 1 479 With regular gasoline, as wasthe case with light and heavy catalytic naphthas, distinct improvementsin the gum content were obtained by the incorporation of smallquantities of a metallocene with a phenylhydrazone. Specifically, withacetophenone phenylhydrazone as the hydrazone and 0.1 wt. percentcobaltocene, the existent gum was increased to 983 mg./l00 cc. feed from6.6 mg./l00 cc. feed (blank). This constitutes a l33-fold increase inthe gum content. The amount of potential gum was also increased by afactor of four by the same phenylhydrazone-metallocene combination.

In the foregoing tables, the amount of hydrocarbon feedstocks used areshown in most instances to be 200 cc. aliquots and the additives areshown to be in terms of grams with the weight percent shown inparenthesis following the number of grams used. It is, of course,apparent that an accurate weight percent figure would be, in all cases,slightly higher than as shown because the volume of feed (200 cc.) wouldnot weigh 200 grams but would actually vary between about and aboutgrams depending upon the actual densities of the feedstocks employed.

Having now thus fully described and illustrated the instant novelprocess and compositions, what is desired to be secured by LettersPatent is:

1. A process which comprises treating, in the liquid phase, a petroleumdistillate fuel containing olefinically unsaturated components andmolecular oxygen with at least one metallocene and at least onearylhydrazone having the formula:

wherein R is selected from the group consisting of C C saturated acyclichydrocarbon radicals, C -C saturated cycloaliphatic radicals, aralkyland aryl, R is selected from the group consisting of C C saturatedacyclic hydrocarbon radicals, C C saturated cycloaliphatic hydrocarbonradicals, aralkyl, and hydrogen, including R 5. A process as in claim 1wherein the distillate fuel is a cracked naphtha boiling within therange between about 75 F. and about 750 F.

6. A process as in claim 5 wherein the arylhydrazone is obtained byreacting a cycloaliphatic saturated hydrocarbon ketone withphenylhydrazine.

7. A solids free petroleum distillate fuel originally containingolefinic unsaturated components and molecular oxygen which has beentreated with at least one metallocene and at least one arylhydrazinehaving the formula:

wherein R is selected from the group consisting of C C saturated acyclichydrocarbon radicals, C -C saturated cycloaliphatic radicals, aralkyland aryl, R is selected from the group consisting of C -C saturatedacyclic hydrocarbon radicals, C C saturated cycloaliphatic hydrocarbonradicals, aralkyl, and hydrogen, including R and R being jointly a C -Calkylene rdaical, the weight ratio of arylhydrazone to metallocene beingbetween about l:1 and about 10:1, and from which so treated fuel atleast the solid gum has been removed.

8. A petroleum distillate fuel as in claim 7 wherein the arylhydrazoneused is the phenylhydrazone of cyclopentanone and the metallocene isselected from the group consisting of ferrocene, nickelocene, andcobaltocene.

9. A petroleum distillate fuel as in claim 7 wherein the arylhydrazoneused is the phenylhydrazone of cyclohexanone and the metallocene isselected from the group consisting of ferrocene, nickelocene, andcobaltocene.

10. A petroleum distillate fuel as in claim 7 wherein the arylhydrazoneused is the phenylhydrazone of acetophenone and the metallocene isselected from the group consisting of ferrocene, nickelocene, andcobaltocene.

11. A petroleum distillate fuel as in claim 7 wherein the distillatefuel is a cracked naphtha boiling within the range between about 75 F.and about 750 F.

12. A petroleum distillate fuel as in claim 11 wherein the arylhydrazoneis obtained by reacting a cycloaliphatic saturated hydrocarbon ketonewith phenylhydrazine.

References Cited UNITED STATES PATENTS Pauson 252431 Thomas 260439Wojcik 4464 Anzilotti et a1. 4468 Riemschneider.

10 3,088,960 5/ 1963 Wollensak. 3,088,961 5/ 1963 Wilkinson.

Y. H. SMITH, Assistant Examiner 10 US. Cl. X.R.

